The present invention relates to an ignition coil for internal combustion engines.
More particularly, it relates to an ignition coil which has a housing composed of an insulating material, a ring-shaped core insertable into the housing and composed of soft magnetic material and primary and secondary windings wound on the core.
Ignition coils of the above mentioned general type are known in the art. One of such ignition coils is disclosed for example in the German document DE 39 37 828 C1. The ignition coil disclosed in this reference has a housing provided with a lateral insertion opening and a coil body provided with a primary coil and a secondary coil and insertable through the insertion opening into the housing. The mounting of this ignition coil is performed so that the coil body is first finally wound outside of the housing and premounted functionally with connection plug for primary and secondary connections. After the operational testing this structural assembly is inserted through the insertion opening into the housing and fixed there with testing resin.
In the known embodiment, during the premounting of the secondary connection it is necessary in a first manufacturing step to insert a diode between a connecting pin of the secondary connection at the high voltage winding end of the secondary coil and to provide electrical contacting. In a second manufacturing step then the connecting pin is mounted on the coil body of the secondary coil.
During performing the second manufacturing step the mounting forces on the connecting pin are transferred in disadvantageous manner to the diode which is connected with its one end with the secondary coil so that there is a danger that the diode or its contact is damaged. Furthermore, after performing the second manufacturing step the diode is arranged relative to the coil body of the secondary coil so that it is transverse to the chambers which locally receive the secondary coil and is immediately adjacent to several chambers. Since the voltage level increases from chamber to chamber for high voltage winding and of the secondary coil, there is a danger that along the diode a shunt for a voltage equalization forms between the individual chambers. For preventing this, in the known ignition coils the ribs which form the chambers and extend outwardly project substantially over the clamped level from the coil winding. This leads to a great structural volume of the ignition coil which is of course undesirable.